Light-sensitive vesicular imaging materials

ABSTRACT

Light-sensitive vesicular imaging materials, suitable for the production of colored labels, etc., comprise a light-sensitive vesicular imaging layer applied to one surface of a transparent self-supporting plastics sheet or film such as a linear polyester, e.g. polyethylene terephthalate film, said light-sensitive vesicular imaging layer comprising a polymeric vehicle having uniformly dispersed therein a sensitizing agent which releases a vesicle-forming gas, preferably nitrogen, upon exposure to light and optionally including a pigment or dye, said polymeric vehicle comprising a thermoplastic polymer having a nitrogen permeability constant in the range 1×10 -15  to 1×10 -10  and being softenable upon heating above ambient temperature to permit the gas released by the sensitizing agent in the light-struck areas to form an image in the form of light-scattering or reflecting vesicles therein, wherein at least one pigmented or dyed coating layer which includes a polymeric binder and has an opacity represented by a total luminous transmittance measured by ASTM test method D-1003-61 not exceeding 25% is applied over the vesicular imaging layer and remote from the plastics sheet or film and provides a contrasting background for the image. The pigmented or dyed layer may optionally contain a self-adhesive or pressure-sensitive adhesive for affixing the material to a receptive substrate. Alternatively a separate self-adhesive or pressure-sensitive adhesive layer may be applied to the pigmented or dyed layer, optionally protected by a peelable backing layer.



